• Computers and Concrete
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• v.15 no.6
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• pp.903-919
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• 2015

The flow of freshly mixed cement-based material shows thixotropy, which implies some difficulties on robust measurement of its rheological properties: The flow curve of thixotropic materials depends on the used protocol. For examples, higher viscosity is obtained when the rate of shear strain is more quickly increased. Even though precise measurement and modelling of the concrete rheology needs to consider the thixotropic effect, engineers in the concrete field prefer considering as a non-thixotropic Herschel-Bulkley fluid, even more simply Bingham fluid. That is due to robustness of the measurement and application in casting process. In the aspect of simplification, this papers attempts to mimic the thixoropic flow by the non-thixotropic Herschel-Bulkley model. Disregarding the thixotropy of cement based materials allows us to adopt the rheological concept in the field. An optimized protocol to measure the Bingham parameters was finally found based on the accuracy and reproducibility test of cement paste samples, which minimizes the error of simulation stemming from the assumption of non-thixotropy.

• Polymer(Korea)
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• v.38 no.2
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• pp.213-219
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• 2014

The rheological characteristics of highly concentrated polymer bonded explosive simulant were studied. Hydroxyl terminated polybutadiene (HTPB) and polyethylene plastomer (Exact) were used as binders. Sugar and Dechlorane particles whose physical properties are similar to research department explosive (RDX) were used as fillers. When HTPB was used, diethyl hexyl adipate (DEHA or DOA) was used as a plasticizer together for some cases. Highly concentrated suspensions were mixed in a batch melt mixer (Rheomixer 600, Haake) and rheological properties were measured by plate-plate and capillary rheometers. Wall slip phenomena, thixotropy with shear hysteresis, and flow instability were investigated as shear rate and amount of fillers changed.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.141-145
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• 1985

In the present study, an attempt was made to investigate the characteristics of rheological properties of a themally oxidized soybean oil. Various flow curves of the oxidized oils were obtained using a broad range of shear rate (452-904 rpm). The flow curves showed the characteristics of thixotropic flow, and as temperature decreased (range : 13-$37^{\circ}C$) they demonstrated increasingly stronger thixotropic properties. A thixotropic slope similar to the coefficient of thixotropy as applied to the rheological characteristics of the thermally oxidized soybean oil to predict its rheological properties quantitatively at an equilibrium state. The empirical formula with the thixotropic slope was found satisfactory in predicting the Non-Newtonian behavior of the thermally oxidized soybean oil.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1229-1234
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• 2003

The utilization of metakaoline as a mineral admixture for cement has received considerable attention in recent years. This paper investigates the rheological properties of cement pastes containing metakaoline in view of fluidity. The rheology of the paste is assessed by using a BROOKFIELD RVDV II + viscometer (SC4-21, 29) having cylindrical spindle. The results show the fluidity of cement pastes with metakaoline is increased by increasing W/S ratio and the dosage of superplastcizer. And also cement pastes with metakaoline as a partial replacement of cement show a dilatant behavior. Dilatancy is heavily influenced by W/S ratio and by the amount of metakaoline. However the thixotropy of the pastes is increased by silica fume.

• Journal of the Korean Chemical Society
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• v.50 no.6
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• pp.447-453
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• 2006

of synthetic conditions and water content on rheological properties of polyacrylamide hydrogels were studied. The non-Newtonian flow curves of polyacrylamide hydrogels were obtained by using a cone-plate rheometer. The rheological parameters were obtained by applying non-Newtonian equation to the flow curves for polyacrylamide hydrogels. The polyacrylamide hydrogels are shear thinning under increasing shear rate modes which result in thixotropic behavior. These flow properties are controlled by the characteristics of flow units and the interaction among the flow segments.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.103-109
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• 2007

In this study, the rheological properties of cement pastes containing blastfurnace slag of different fineness were investigated. The fluidity of cement pastes with low Blaine value blastfurnace slag was increased with decreasing the plastic viscosity and the yield stress of pastes. And the optimum dosage of polycarboxylate type superplasticizer to the cement pastes was confirmed according to the fineness and the replacement ratio of blastfurnace slag. All cement pastes showed the thixotropy behavior. And also it was formed that the segregation range of cement pastes was occurred below $10D/cm^2$ of the yield stress and below 350 cPs of the plastic viscosity by the coaxial cylinder viscometer.

• Journal of the Korean Graphic Arts Communication Society
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• v.23 no.2
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• pp.117-128
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• 2005

Printing inks are basically dispersions of solid pigment particles in a vehicle. Pigment flocculation and/or colloidal aggregates created by thixotrope additives form a three- dimensional network in the inks. This structure complicates the flow behaviour of inks. However, if the internal structure is formed under control, the printing process will benefit from it because the ink must satify rheological requirements over a very wide range of shear conditions. The presence of internal structure results in the following prominent non-Newtonian rheological properties: viscoelasticity, yield stress, shear thinning and thixotropy. If the components of printing inks were changed, the rheological characteristics such as viscosity, yield stress, viscoelasticity and tack value were considerably varied. Thus, in this paper, the effects of changing the content of rosin modified phenolic resin on rheological properties of the vehicle will be studied. For that, the rheological properties were found by flow, yield stress, creep and oscillation measurements using Bohlin C-VOR Rotational Rheometer. And Emulsion rheology and its microstructure will be investigated.

• YAKHAK HOEJI
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• v.35 no.4
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• pp.277-282
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• 1991

Rheological, colloidal and micromeritical properties were followed to investigate aging mechanisms of hydrous aluminum oxide suspension using Zeta-meter systems, BET adsorption apparatus, Master sizer and electronmicroscope. The results indicate that hydrous aluminum oxide suspension revealed plastic flow with thixotropy. The viscosity, thixotropy and yield value were increased with increasing concentration. During aging process, the viscosity and thixotropic index were increased by an addition of glycerin, however, sorbitol stabilized aging process of the suspension being accompanied with growth of particle size and reduction in specific surface area, pore area and pore volume, and consistency. Diminution of adsorptive power of the particles was also protected by addition of sorbitol to hydrous aluminum oxide suspension. From these results, one of aging mechanism of hydrous aluminum oxide suspension assumed growth and/or crystallization of colloidal particles in aqueous suspension.

• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.2
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• pp.7-18
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• 2002

The emulsification of lithographic printing inks are very important to determine printing quality. In this study, we measured the variation of water pickup according to the hardness of water in dampening solution. In order to observe the rheorogical properties of the emulsified inks, we measured the viscosity, the elastic return, the thixotropy area and yield stress value of the emulsified inks. In this paper, we found that the water pickup of the ink increase the hardness of water with the amount of dampening solution. Also, The viscosity, the yield stress value and the thixotropy area were increase by the water pickup of the ink.

• YAKHAK HOEJI
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• v.46 no.1
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• pp.6-10
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• 2002

The present study investigated the rheological properties and adjuvant activity of IgG production of ι-Carrageenan prepared using two different methods . incubation at 37.4$^{\circ}C$ after either being heated or not being heated int 6$0^{\circ}C$ for 10 minutes. The carrageenan exhibited plastic flow with thixotropy in both cases, but the viscosity of the sample that had been heated was significantly higher. C57BL/6 mice were then immunized intraperitoneally with either of the carrageenans containing protein antigens. The maximum adjuvant effect was found when using the nonheated carrageenan, especially in term of IgG2a, IgG2b, and IgG3 production. In contrast, IgG1 antibody production was the same far both types of carrageenan. furthermore, when administered oral1y, neither type of carrageenan resulted in the production of any antibodies.